Sphingolipids containing radioactive isotopes were synthesized and used for metabolic studies and as diagnostic tools in spingolipidases. 14C and 3H labels were introduced by synthetic and semi-synthetic techniques, gas exposure and a new approach: functional group exchange. These techniques were used for the syntheses of radioactive enantimorphic derivatives of sphingolipids. These produces are not metabolizable. Experimentation with these in animals creates "animal models" for metabolic disease and opens new areas for biomedical studies.